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As this is for your site, it is hard for anyone to give you their documentation. There is a troubleshooting guide for the database in the documentation and you could take parts of it and supply that.

Without knowing all about your site I would find it very difficult as professionally I am going to look bad when the documentation causes a bigger problem after some tries to resolve some thing and it does not work.

Start with the basics, how to start and stop the database This would include hostname, user account, scripts to run etc for that server.
Backups testing, recovery plans, do I always want to recover the database, not likely. If you have been baby sitting a database and now want leave and you have no instructions, I feel for you but these instructions are what good dba's do when not backing up, recovering databases, testing and self educating themselves to do all this.